1. Field of the Invention
The present invention relates to an interchangeable lens, a camera body and a camera system.
2. Description of Related Art
An interchangeable lens used in a camera system normally includes at least one optical member (drive target member or driven member) the drive condition (driven condition) of which changes, such as a focus adjustment lens, disposed within the interchangeable lens. Information (drive condition information or driven condition information) related to the drive condition (driven condition) of such an optical member (drive target member or driven member) is required to enable various types of control at the camera body. The camera system disclosed in Japanese Laid Open Patent Publication No. H10-68871, for instance, includes an encoder that monitors the motion of a lens transmission system. A monitor signal indicating a drive quantity, which is output by the encoder, is fed back to the lens drive control CPU via a lens-side contact point located at a mount unit via which the lens is mounted at the body and a body-side contact point corresponding to the lens-side contact point. In addition, on the other hand, the main CPU within the camera body is connected with the lens CPU and the like disposed in the photographic lens via a contact point other than the contact point via which the monitor signal is transmitted in the camera system described in Japanese Laid Open Patent Publication No, H10-68871. The main CPU receives information required for camera sequence control and exposure operation control from another CPU or the like and provides another CPU with camera sequence information needed at the other CPU. In other words, the contact point via which the main CPU and the lens CPU are connected enables universal communication. Information to be transmitted from the lens CPU through the universal communication contact point to the main CPU collected by the lens CPU first.